Figure 1: Two Underground Alignment Options for CRL in the Vicinity of the CCNR
The key facts about the two alignment options are as follows:
i) Direct alignment option
- 4km tunnel in total, with 2km deep under the CCNR and the remainder outside the CCNR
- No physical structures on the surface level within the CCNR
- Travelling time: approximately 5 minutes (from Bright Hill to the next station)
ii) Skirting alignment option
- Tunnels skirting around (and away from) the CCNR
- A 9km tunnel route length under roads as well as residential and commercial buildings
- Travelling time: approximately 11 minutes (from Bright Hill to the same next station)
Where Are We Now?
To allow an informed decision on the final alignment for the CRL, LTA commissioned in 2014 an Environmental Impact Assessment (EIA) for both alignment options. The LTA adopted a robust two-phase EIA process for the two alignment options.
Phase 1 evaluated the existing ecosystem and physical conditions of the CCNR as well as the environmental impact of site investigation (SI) works within the CCNR. Phase 1 had been completed with the report gazetted and published on the LTA website in 2016. The findings of the SI works (carried out following the report) were used to inform Phase 2 of the EIA.
Phase 2 assesses the potential environmental impact of the construction and operations of the CRL as well as the required mitigation measures. LTA sought inputs from, and engaged with, the relevant stakeholders as part of this process. This phase of the EIA has recently been completed.
Gazette of the EIA (Phase 2) Report
With the completion of the Phase 2 EIA, LTA gazetted the EIA Report on 2 September 2019. The gazetting is to allow public viewing and feedback on the findings of the Report. The Report does not recommend a preferred alignment option.
No decision on the alignment option has been made. The decision on the final alignment will be based on factors such as connectivity, travel times, costs as well as impact on home owners and the environment.
LTA have devised robust engineering schemes for the two alignments. These schemes define the geographical focus and construction techniques to be adopted that informed the EIA. The engineering schemes are robust and independently reviewed by LTA’s International Panel of Advisors (IPA). The IPA comprises internationally renowned experts in geotechnical and tunnel engineering, who concluded that with control measures in place, tunnelling along either alignment option is safe.
The EIA, by Environmental Resource Management (S) Pte Ltd (ERM), was rigorously undertaken based on an internationally-recognised framework and relevant authoritative references. ERM is a global specialist in environmental, social, health, safety and risk management consulting services that have done similar EIA works in the UK, China and Hong Kong. The EIA Report, too, was independently reviewed by an appointed consultant. (Figure 2 provides an overview of the approach for the Phase 2 EIA prior to the Gazette).